
Preheat oven to 375F (190C) and line a 12-count muffin tin with paper liners. Set aside.
In a large mixing bowl, whisk together flour, cornmeal, sugars, baking powder, baking soda, and salt.
In a separate bowl or large measuring cup, whisk together sour cream, melted butter, and egg.
Pour the wet ingredients into the dry ingredients and use a spatula to gently fold together until completely combined and no dry streaks remain. Batter will be dry and stiff, this is normal!
Evenly divide batter into prepared muffin tin. Transfer to center rack of 375F (190C) oven and bake for 14 minutes, until muffins are baked through and a toothpick inserted in the center comes out clean or with a few moist crumbs (no wet batter).
Allow to cool in muffin tin for 5 minutes then carefully remove to a cooling rack before enjoying.